1. Field of Invention
The present invention relates to apparatus used in the automated application of labels to objects. More particularly, the present invention relates to apparatus for applying adhesive-backed labels to merchandise-containing packages on an automated merchandise-encapsulating assembly line.
2. Description of Related Art
In the modem assembly-line production of products for the mass-market, an important stage is the encapsulation of the products and the labeling of the encapsulating materials. Although a good deal, and often all, of the information needed on the package (UPC, source identification, etc.) can be printed on the wrapping material itself, there often remains the need to affix other labels. These labels include in particular, but are not limited to, theft-mitigation tags and the like. Until recently, such tags were applied by the end retailer, either to the outside of the product or to the outside of the product""s packaging. Lately, there has developed a demand by large retailers that these labels be already affixed when the products arrive from the manufacturer or wholesale-distributor. Furthermore, In those cases where the label is to be affixed to the product itself or even to an internal surface of the product, it is completely impracticable for the retailer to carry out this step. For these reasons and others, there is a great incentive to devise label-applicators (xe2x80x9clabelersxe2x80x9d) operable in the rapid, automated fashion necessary to their incorporation in an assembly line.
The first label-applying devices intended to be incorporated into assembly/packaging lines reflected the diversity of label designs in use. In other words, the initial devices were designed with the hope that they could be used with most or all of the types of automated labels in common use, with the result that all these devices fall short of being ideal for any particular type of label. In addition, there are other drawbacks to the existing label-applicators, to be described below.
Labels of the type under discussion are supplied in the form of rolls of lift-off tape to which the individual labels are affixed. Conventional labeling devices for applying adhesive-backed labels use a peeler-bar to dislodge each label in turn from this lift-off tape as the item to be labeled passes through the labeling device. Once dislodged, each label is typically allowed to fall freely under the force of gravity (to go into xe2x80x9cfree-fallxe2x80x9d) until it is grabbed by the apparatus, such as a suction device, that is going to affirmatively apply the label to the item. (Alternatively, the label is deposited onto a platform from which it is then engaged by such apparatus.) In any event, the label is then held in position while it is adhering to the item to be labeled. If the label is not aligned properly at the point where pressure is applied to it and the adhering occurs, it will be affixed crookedly and/or imperfectly.
The traditional labeling devices also suffer from being complex and hence relatively prone to breakdown. Part of the complexity is due to the incorporation of a number of sub-systems, such as pneumatic-driven and gear-driven transfer mechanisms, heating elements, and more. This makes the devices more expensive at the outset and more expensive to maintain.
Solomon (U.S. Pat. No. 5,370,754; issued 1994) teaches a labeling machine that moves a label across a peeler-bar to dislodge it from its backing strip. After the label is dislodged, it free-falls until it comes to rest on a platform, from which it is picked up by a suction device and transferred to the item to be labeled. The free-fall, no matter how momentary, that occurs after the label is dislodged from the peeler-bar is a source of inaccurate label placement. The misplacement can be due to air currents, to misalignment, or to other factors. Complicated adjustments to the peeler-bar are often required to avoid this problem after the labeler equipment has been put into operation. Solomon further teaches that the transfer of the label from the detaching station to the application station is performed by a Cartesian robot having an arm with a suction function. This robot is an example of the sub-systems that can significantly add to the price of the labeling device as well as to its complexity-related breakdown rate..
Yamaguchi (U.S. Pat. No. 5,300,181; issued 1994) teaches a labeling device wherein each label is positioned by means of a suction plate prior to affixation. Although this overcomes the misplacement problems associated with free-fall, the use of a suction plate for holding the label in position introduces dependency on a vacuum-xe2x80x9cgeneratingxe2x80x9d system and thus makes the device vulnerable to vacuum leaks and other failures in the pneumatic/vacuum system. Additionally, the fact that the device of Yamaguchi relies on multiple pressing in conjunction with an elastic body, introduces another possibilty of failure, that due to the elastic body.
Lindstrom (U.S. Pat. No. 4,595,447; issued 1986) discloses a labeling device that uses a vacuum foot at the end of a vertically oriented spindle that moves along a horizontal track to transfer a label from a printed-label dispenser to the article to be labeled. In addition to requiring a vacuum or other means for producing a pressure differential, such a transfer mechanismxe2x80x94one that translates the label in two dimensionsxe2x80x94has many parts, thus increasing the chances of mechanical failure or faulty operation of the apparatus.
The device of Karp (U.S. Pat. No. 4,367,118; issued 1983) also uses a pressure differential to secure each label between the time it is removed from the backing strip and the time it is placed on the item to be labeled. Additionally, the suction device of Karp that transfers the label from the stripper bar to a label-transfer station. The motion of this transfer is both horizontal and vertical, and requires drive mechanisms for both directions of movement. The inclusion of these drive mechanisms adds to the cost of the label applicator and, as well, to its chances for failure during operation.
Therefore, what is needed is a labeling machine that can be integrated with a packaging machine, that avoids the alignment problems associated with xe2x80x9cfree-fall,xe2x80x9d and does not require the use of transfer drive mechanisms, nor inefficient peripheral systems such as vacuum xe2x80x9cgeneratorsxe2x80x9d used by existing labeling machines.
The present invention meets the goals set out above by providing labeling apparatus with relatively few mechanical parts, and no requirement of pneumatic systems to hold a label. Furthermore, the present invention provides a simplified manner of moving a strip of labels through a such an apparatus. Moreover, the present invention can be used in conjunction with semi-rigid labels (e.g., foil, paper, and anti-theft labels that incorporate circuitry) or rigid labels (e.g., anti-theft magnetic-strip-containing labels) such as are commonly used on and in the packaging of consumer products, and on the products themselves. The present invention provides a label-application device that can stand alone or be integrated into systems requiring fully automatic operation. The apparatus of the present invention mechanically removes an adhesive-backed label from a lift-off strip and places it in the position desired, typically though not necessarily on the outside of packaging. The mechanical removal of the label from the strip eliminates the inaccurate label placement associated with the label free-fall intrinsic to most existing labeling machines. The mechanical removal of the label also eliminates the possible need to apply heat to the lift-off strip to facilitate removal of the label. Additionally, this invention mechanically holds a label in position until the label is pressed directly onto a parcel. This eliminates the need for a suction device and the need for a peripheral vacuum source. Because the current invention eliminates the complicated adjustments associated with free-fall and the need for peripheral heat and vacuum sources, the current invention avoids the inefficiencies and costs associated with conventional labeling machines. The present invention can either be embodied in a stand-alone device or be integrated directly into a packaging system requiring automation from start to finish.
The heart of the present invention is the guide block assembly and label receiver. The remaining components may be located in a variety of positions as circumstances associated with a particular application dictate. In most embodiments, the various components of the invention are mounted on a back-plate. For structural integrity, the back-plate may itself be affixed to a base plate, though this is not in general necessary. Components included in the present invention are a means for mounting a label reel, fixed or rotating label stock guides, and a backing-material take-up reel. The guide block assembly consists of a guide block designed specifically for a particular type of label and a fixed design peeler bar attached to the underside of the guide block. Another important component of the present invention is a label receiver assembly consisting of a label receiver, a pawl retainer spring, and two pawls. This assembly is mounted directly or indirectly to the guide block via a linear slide. The two pawls are attached in a pivoting manner to the label receiver. A cylinderxe2x80x94which may be motorizedxe2x80x94is frequently incorporated to provide movement to the label receiver assembly via the linear slide arrangement. A backing material take-up reel is mounted on a motor-driven shaft. Incorporated into this take up reel is a backing material retaining clip. A backing-material take-up motor drives the shaft.
Several components are utilized to control the motions required to remove the label from the backing material. These components can be an optical or mechanical sensing device located in the guide block in addition to a control devicexe2x80x94such as a Programmable Logic Controller (PLC), a combination of relays, or control circuitryxe2x80x94specifically designed for this device.
The labels are presented to this machine attached to the backing material and subsequently rolled onto a center core. This forms a label reel that is suspended on the label reel mounting means.
Labels can be supplied to this machine via any one of several conventional methods that are well known in the art, such as by rolls of backing material (having the labels attached thereupon), or by this backing material being stacked in boxes in a so-called xe2x80x9cfan-foldxe2x80x9d configuration. The labels are typically adhered to a backing material which is in turn rolled up to form a label reel assembly. In order to keep the cost to a minimum, the label reel is suspended via a center core in a simple fashion that does not induce any specific amount of xe2x80x9cdragxe2x80x9d on the center core.
Backing material with the attached labels is threaded around label stock guides, and then between the guide block and peeler bar. The relationship of the guide block and the peeler bar is specifically designed around the label being utilized. The design of the guide block assembly, which is made up of the guide block and peeler bar, conforms closely to the cross section of the label and the backing material. The backing material is then threaded under another label stock guide and on to the backing material take up reel. Here it is attached with the backing material retaining clip.
Upon receipt of an external signal indicating that a part is in position to have a label applied to it, the control device initiates the backing material take up motor which in turn pulls the backing material through the previously described path. As the backing material travels around the peeler bar, the label travels straight, becoming increasingly unattached from the backing material. As the label becomes unattached, it enters a cavity created by the geometry of the label receiver and two movable pawls. Both the receiver and the two pawls are specifically designed for the label being utilized. The movable pawls are made of a material that the adhesive has very little, if any, tendency to adhere to. The design is also such that the lower flat surface of the label to which the adhesive has been applied contacts these pawls minimally.
Prior to the label becoming fully unattached from the backing material it has been completely captured by the label receiver assembly. At this point, depending on label design, the label may have become completely unattached from the backing material and fully traveled into the label receiver assembly. Alternately the label may have to be pushed into final position by the following label. In either situation a sensing device detects the position of the label following the label in the label receiver and sends a signal to the control device which, in turn, causes the backing material take up motor to stop. Since the stopping accuracy of this motor determines the final position of the label, the proper motor has to be specified for the application. Depending on the throughput required and accuracy of label placement required of the machine, this motor could be anything from a simple AC gear motor to a fully controllable servo motor.
After the label is in its final position in the label receiver assembly, the label receiver travels toward the final application point. This motion is caused by activation of the cylinder. Alternatively this motion could be achieved via mechanical linkage or cam(s) driven by a motor or other non pneumatic source. The first parts to contact the application surface are the two pawls. Upon contact the pawls are rotated outward against the pawl retainer spring thereby allowing the label to contact and become attached to the application surface. After label attachment, the label receiver assembly returns to the label receiving position and the cycle is repeated.
Alternately, the invention can be practiced without using pins to stop, and thus place, the label for transfer. Any of a number of mechanisms can serve to provide the accurate stop that is needed.